DAC Data Analysis Fundamentals 3 — Questions and Answers
Question 1: Which chart type best displays the proportion of a whole across a few categories?
- Line chart
- Pie chart (Correct answer)
- Scatter plot
- Histogram
Correct answer: Pie chart
A pie chart shows each category's share of a total.
Question 2: A correlation coefficient of -0.9 between two variables indicates what?
- Strong positive relationship
- Strong negative relationship (Correct answer)
- No relationship
- Perfect causation
Correct answer: Strong negative relationship
A value near -1 signals a strong inverse (negative) linear relationship.
Question 3: What is the purpose of data normalization before analysis?
- To scale features to a comparable range (Correct answer)
- To delete outliers
- To sort rows alphabetically
- To add new columns
Correct answer: To scale features to a comparable range
Normalization rescales values so variables with different units can be compared fairly.
Question 4: Which sampling method gives every member of a population an equal chance of selection?
- Convenience sampling
- Simple random sampling (Correct answer)
- Quota sampling
- Snowball sampling
Correct answer: Simple random sampling
Simple random sampling gives each unit an equal, independent selection probability.
Question 5: A histogram is most useful for showing what about a single numeric variable?
- Its distribution (Correct answer)
- Its correlation with another variable
- Its category share
- Its time trend
Correct answer: Its distribution
Histograms group values into bins to reveal the shape of a distribution.
Question 6: In a dataset, 'gender' stored as Male/Female/Other is which kind of variable?
- Categorical (Correct answer)
- Continuous
- Interval
- Ratio
Correct answer: Categorical
Values that are labels with no inherent numeric order are categorical.
Question 7: What does an outlier detected by the IQR method fall outside of?
- 1.5 times the interquartile range from the quartiles (Correct answer)
- The mean plus one standard deviation
- The median
- The mode
Correct answer: 1.5 times the interquartile range from the quartiles
The IQR rule flags points beyond 1.5×IQR below Q1 or above Q3 as outliers.
DAC Data Analysis Fundamentals 3
Which chart type best displays the proportion of a whole across a few categories?